Flotation agents and process of concentrating ores therewith



. 'Patented 7, i939.

. 2,149,546 nors'non AGENTS AND rn'o'onss or- OON- ccu'msrma cans 'mnnnwrrn 4 Anderson w. Balaton and William 0. cago, v111., assixnors to Amour-and cago', Ill.,.a corporation of Illinois 'No Drawing. Application v Serial No. 141,374

- cclsims.

This invention it comprises as new flotation agents mixtures of straight-chain saturated and unsaturated aliphatic.carboxy1ic fatty acids therein contain-at least five and not acids in which the predominating more than ten carbon'atoms, it further comprises i as flotation agents those fatty acid mixtures 'retrate rich in 1 1 Vin 'lhese agents for example, 'aqueous pulp of the ore tion agents are added sulting from the hydrolysis of nitriles obtained by cracking high molecular weight nitriles, such as stearonitrile, and it further comprises processes wherein finely-ground ore is mixed with a water solution of said flotation agents, and aconcentherefrom.

Flotation agentsare used in great quantities the concentration of ores by flotation methods.

values in the ore insuch a way that the values are floated, leaving the ganguebehind. Thus, in the froth flotation of ores an is first prepared, fiota thereto, and the mixture is aerated whereby metalliferous values in the ore collect as a froth which can be readily skimmed ofi and thefietal values therein recovered. Similarly,'non-meta lliferous values, such as phosphate respect to its interfacial tension aeration. 'I'he'minute rlseas'a froth. I

Olelcacid, fuel oil and other, hydrocarbon oilsfrequently used '*."substances which appear and sometimes rock, can be separated from the siliceous gan'gue.

Oleic acid was one of the first flotation agents used in the froth flotation of ore, and many other flotation agents have since been tation methods require that the ore values to be floated should be surface of the modified with so that the surface is preferentially wetted by water. When froth flotation is employed a frothlng agent must also be present to assist in the formation of-a-relatively stable froth during the the surface-modifledore value causing them to as collectors. These are I to have a selective action on the values in the commonly a soap.' Frequently the flotation agents used are mixtures, the constituents of which-perform the two functions Just stated; a single substance will perform both functions.

There have been many dill'erent flotation scents proposedand of late most of theses-gents are thetlcallyeprepared chemicals such as relates to flotation agents and. i processes of concentrating ores therewith. and

the desired ore value separated modify the surface of the desired vantageous when used franklinite, apatite, and

towards water bubbles formed adhere to ore it is desired to float so that they modify the interracial tension thereof ,with respect to'water. The frothing substance is Pool, 0111- I Synthetic flotation agents are quite expe sive, and the art has desired more 'eflicient flotation agents which could be prepared at little .cost and which flotation agents with most of the ores commercially subjected to this type of would function as concentrating process. Many oxide and carbonateores, for example, are not readily floated by flotation. agents hitherto proposed without some special treatment of the ore prior toconcentration.

In the Harwood tion, S, N, 139,611,

and Pool co-pe'nding applicaflled April 28, 1937, there are described flotation agents comprising nitriles having from three to ten carbon atoms such, for example, as propi'onitrlle, 'butyronitrile, valeronitrile and others. We have now discovered another class of flotation agents which can be made from these nitriles and which are especially ad-' to float, as by froth flotation methods, the-following minerals: pyrolusite, malachite, chalcopyrite, chalcocite, galena, rutile,

ilmenite.

The flotation agents of the present invention can be broadly characterized as mixtures of satu-, f

rated and unsaturatedstraight-chain aliphatic 25 carboxylic acids in which acids having from flve to ten carbon atoms. predominate. Thus our flodecanoic and decenolcv acids. The doublebond in" unsaturated acids the terminal position. we believe that the'very efiective flotation propertiesof this mixture of acids are due to the presence of the unsaturated low chain acids when associated with the low chain saturated pared from their corresponding nitrilesby sub- .jecting mixtures of nitriles having from-five to molecule thereof to al-,

ten carbon atoms in the These acid mixtures are most conveniently prekaline hydrolysis in ways well known forthe preparation of carboxylic acids from the corresponding nitriles. Thenltrile' starting mixture is best preparedvby subjectinghigh molecular. weight fatty I acid nitriles. namely thosehitriles having from twelve to eighteen carbon atoms, to Dyrolytlc' 2,033,537. These methods in general consist in subjecting a higher fatty acid nitriie such as lard fatty acid nitriles and the like to heat in the liquid-phase, or. to heat-and a vaporvphase andfcondensin'g a decomposition or crachlngiin; acco v ents, the reaction products distillate composed of lower molecular weight nitriles and hydrocarbons. As stated in said patfrom such .pyrolytic cracking consist of saturated and unsaturated nitriles having from three to ten carbon atoms,

together with quantities of saturated and unsaturated straight-chain hydrocarbo ns Having first prepared a mixture of nitriles and hydrocarbons in the manner stated we can then the mixture under 50 pounds pressure for about.

; salts are soluble in water carbons in the original starting mixture are not.

subject the entire mixture to. alkaline hydrolysis- -by mixing with itcaustic soda solution having about ten to twenty percent strength and heating 30 minutes in a suitable autoclave. The alkali converts the nitriles'present to sodium salts of acids'corresponding to the nitrile. These sodium whereas the hydro- Consequently, we can readily separate ofl the upper layer of hydrocarbons. To the lower layer of aqueous sodium salt solution of the aliphatic acids we then add hydrochloric or sulfuric acid 1 to decompose the sodium salts and. liberate the tains nitriles having from five to ten carbon atoms. This corresponds to-a mixture containing constituents havingla boiling point range of about 140 to 240 C. Since valeronitrile boils at 141 and caprinitrile at 236 C.

' a distillate from this source having this boiling point range will contain hydrolyzed will yield a mixture of saturated and unsaturated carboxylic'acids having from five to t The percentage of acids conflfty percent and the amount of-acids of diflferent carbon lengths will be approximately equal. In other words, equal quantities of the different aliphatic acids are present therein. 1

Other mixtures of carboxylic acids can be prepared in like manner. when we wish to prepare a mixture consisting predominantly of Co and Ca acids, that is the pentanoic, pentenoic, hexanoic and hexenoic acids, we first obtain a nitrile distillate having constituents boiling between about and 160 C..since within that range the corresponding nitriles are present. when subjected to hydrolysis, as stated, will yield a carboxylic acid mixture consisting predominantly oi the above-mentioned acids. wish to make a. fiotation agent containing mostly Cs and Cs acids, inclusive, we condense a nitrile mixture having. constituents boiling at 163 to V 199 C, In similar ways we can prepare nitrile -mlxtures which, upon'hydrolysis, will yield carboxylic acid mixtures having any desired acids from five to ten carbon atoms and approximately fifty percent of -Orwe can first separate the nitriles from the which will contain one double hydrocarbons in the cracked, reaction products obtained from cracking stearonitrile or simil high molecular weight nitrilesj Such methods of separating thenitrile from the hydrocarbons are be removed from the saturated straight-chain carboxylic acids concracked nitrile I nitriles which when" bond will be approximately Such a mixture,-

boxylic acids,

disclosed in the co-pending application of William 0, P001, S. N. 100,763, filed September 14, 1936.

That method consists in subjecting the mixture of aliphatic nitrilesand hydrocarbons to the ac- 121011 of a solid adsorbent which will preferentially 5 Thus, for example, we can first condense a distillate containing nitriles having five, six, and seven carbon atoms, together with hydrocarbons. We subject this distillate to treatment for the separation of the nitriles therein, and then hydrolyze the separated nitriles to give us a car-, boxylic acid mixture containing such acids as pentanoic, pentenoic,'hexanoic and hexenoic. Or we can condense. another cracked nitrile distillate having a boiling point range which will in: clude nitriles of six, seven and eight carbon atoms, separate the nitriles from the hydrocarbons and subject the nitrile mixture to hydrolysis.

From the foregoing it will be apparent that we can prepare mixtures of carboxylic'acids having any desired-composition by first starting with stearonitrile, lard fatty acid nitriles or other high molecular weight nitriles. Although our invention is broad enough to include making the carboxylic acids in other ways we know of no way which is as simple and as economical as that described. Our flotation agents are unusual in that they are mixtures of saturated and untaining both odd and even numbered carbon chains. Unsaturated low \chain acids and odd carbon atom chain acids are quite rare and with the exception of valeric do inot occur in nature.

'In broad aspects then, 0 invention comprises the concentration of ores by flotation methods in which to the ore pulp we add small amounts of a carboxylic acid mixture in hich acids having from five to ten carbon atoms predominate and in which approximately fifty percent or the acids present contain one double bond. One such mixture may contain equal parts of pentanoic, pentenoic hexanoic and. hexenoic acids; another may contain equal parts of nonanoic, nonenoic, decanoic and decenoic acids. Still another may contain fifty percent by weight of pentanoic and pentenoic acids, forty percent by weight of hexanoic and hexenoic acids and ten percent by weight or "octanoic and. octenoic acids. Mixtures can, of course, be made readily by first hydroly'zi'ng a mixture or nitrilescontaining saturated and unsaturated nitriles from five to ten carbon atoms in length, recovering the mixed free cariractionally distilling the mixed acids to obtain substantially pure free fatty acids and then preparing flotation agents containing any desired proportion of two or more acid mixtures Our fiotationagents are used in substantially the same way as other flotation agents are used in the concentration of ores. In accordance with in this art the ground ore,

which should not. be ground too fine because cont a flotation agent to form a slurry or 74 ploy from about to about 300 parts of flota- 5 son 45 prising predominantly those tion agent per million parts of water. The amount of water solutionv with respect to the ore is, of course, suflicient to give a 'pulp which can be readily aerated, and the requirements as to this are well understood in the art..

Thus, for example, we prepare a ground mixture of galena and gangue, add thereto sumcient water solution containing about 240-parts per million of the flotation agent, and subject the pulp to froth flotation. -We are able to obtain concentrates high in galena. All of the other mineralsmentioned above are floated in the same general way. I

Some minerals will require more .than about 240 parts per million of the flotation agent and others may require less. given above be floated satisfactorily when the amount of flotation million, but other minerals may possibly require variation in this specific amount. It is presumed that those skilled in the art will test small batches of minerals prior to subjecting large quantities to flotation. The flotation-agents of the present invention are somewhat specific in their action. When but 240 parts per million of water are used they will not float the following minerals: celestite, cassiterite in pegmatite, corundum Although our flotation agents consist primarily of two or more carboxylic acids containing from fivetoten carbon atoms we do not wish to have at our invention so narrowly construed as to exclude small'amoun'ts of less than five carbon aliphatic carboxylic acids of from five to ten carbon atoms.

We flnd that our acid mixtures are extremely more efiective as flotation agents than substantially pure acids. They are quitesuperior; for example, to caprylic or capric acid. We attribute their superior action to. the presence of odd carbon chainacids and especially-to the presence or unsaturated acids. These unsatm'ated acids, we find, possess dispersing properties which difler materially from saturated acids of the same chain length The presence oi the double bond 'ciated with saturated acids the mixture possesses quite superior flotation properties. These unusual results are possibly best explained by reference to surface tension phenomena. The com- All of the minerals agent is "240 parts per.

carboxylic acids having atoms. We'try to avoid acids having five,

either of the saturated acids alone or a mixture of the two saturated acids.

Consequently, our invention is directed to the use of a mixture of, saturated and unsaturated acids of between flve and ten carbon atom chain 5 lengths.

In the specific examples given above the composition of the flotation agents used is such that about equal quantities of pentanoic, pentenoic, hexanoic, hexenoic, heptanoic, heptenoic, octanoic, octenoic, nonanoic, nonenoic, decenoic and decenoic acids are present. When this mixture is used maximum flotation is obtained.

' The cracked nitrlle mixtures we hydrolyze yield acid mixtures containing approximately flfty percent of unsaturated acids. We do not, however, want to be limited to these exact proportions. If the acid mixture contains percent or more of unsaturated acids it is eflective. For reasons of economy we prefer to use the hydrolyzed nitrile mixtures and these inherently contain about to 60 percent, usually about 50 percent of unsaturated acids. Although we have more specifically described our invention with reference to the use of our flotation agents as the'predominating flotation ,agent used, we can. of course, add additional agents to the ore pulp to assist in flotation. For example, we can use fuel oil, soaps, and similar 'agents in addition to the mixed aliphatic acids described. Having thus described our invention, what we claim is:

1. In the froth flotation of ores the step which comprises subjecting to froth flotation an aqueous. pulp of the ore'containing a mixtm'e of saturated and unsaturated aliphatic carboxylic acids in which acids having at least flve and not more than ten carbon atoms predominate.

2. In the froth flotation of ores, the step comprising subjecting the ore to froth flotation in the presence of-a-mixture of saturated and unsaturated aliphatic carboxylic acids containing seven, eight, nine and ten carbon atoms.

3. A flotation agent comprising a mixture of saturated and unsaturated aliphatic'cai'boxylic acids in which acids having from flve to ten carbon atoms predominate.

4. A flotation agent comprising a mixture of aliphatic carboiwlic acids obtained from the. hy- I drolysis of a mixture oi nitriles resulting from the cracmng of stearo-nitrile 5; A flotation agent comprising a mixture of at least two organic acids chosen from the group consisting of pentanoic, pentenoic, hexanoic, hexenoic, heptanoic, heptenoic, octanoic, octenoic, nonanoic, nonenoic, decanoi'c or decenoic acids, one of which is unsaturated.

6. In the froth flotation of ores, the step 'comprising subjecting the ore to froth flotation in the Presence of at least two organic acids chosen from the group consisting of 'pentanoic, pentenoic, hexanoic, hexenoic, heptanoic, heptenoic, octanoic, octenoic, nonanoic, nonenoic. decanoic or II decenoic acids, one of which is unsaturated.

snnnnson w. RALBTON.

WIILIAM 0.2001. 

